Should I cut off all my hair?

My hair is about half way down my back. It is quite damaged from years or straightening and colouring and its also rather frizzy. I have never had short hair before and to be honest I am terrified to cut it but I am really sick of it and also I think that it is time for a change. Have you ever cut your hair off and did you regret it or find it liberating? Should I cut it and if so, how short?